A multifunction peripheral and an information processor have recently been connected via a communication network, so as to carry out various processes. Namely, a multifunction peripheral can operate as part of a total application system by causing an application operating in an information processor and a function of the multifunction peripheral to cooperate with each other. This facilitates easy construction of flexible service in which a function of a multifunction peripheral and a function of a PC are combined appropriately. For example, Patent Literature 1 discloses a multifunction peripheral control system including a multifunction peripheral and an information processor which transmits a control instruction to the multifunction peripheral via a communication network. Patent Literature 2 discloses a technique for calling a function of an image forming apparatus in accordance with the details of a message received from an external device.